After seeing his South Africa side beaten 3-1 by England, Faf du Plessis says Joe Root's men can retain the Ashes.

England's relentlessness makes them a strong bet for the upcoming Ashes series with Australia, according to South Africa skipper Faf du Plessis.

Joe Root's first series as Test captain saw England comfortably beat South Africa 3-1, the triumph wrapped up at Old Trafford on Monday with a 177-run win.

Apart from the second match at Trent Bridge, England outplayed the Proteas in all departments with Moeen Ali their stand-out performer with bat and ball.

Du Plessis acknowledged his side were second best to the improving England, and he believes they stand a good chance of retaining the Ashes should they maintain their current form when they travel to Australia in November.